var handlers = {
  onConnect: function () {
    console.log('Connected!');
  },
  onMessage: function () {
    console.log('Message!');
  }
};

var map = {
  connect: 'onConnect',
  message: 'onMessage'
};

var trigger = 'connect';
var methodName = map[trigger];
var func = handlers[methodName];

func();